Use GMAT Prep well. Soni took it three times and on the third take he scored 780.
On GMAT break-downs:
Quantitative Test - though combinatorics can be overblown, they’re actually very rare in the test. Having said that a strong affinity for maths is needed.
Verbal Test - get help from Manhattan GMAT's Sentence Correction guide, which teaches you a lot of the intricacies of the English language such as comparisons, modifiers and pronoun placement.
On Test Day:
Apart from the usual get-up-early and never-be-late clichés, Soni didn't spend too much time on difficult questions in the quantitative text as about 10 of them are experimental and therefore won't count.
Apparently some lucky guesses on multiple-choice, plus energy bars and Starbucks also helped. The test is four hours.
Last but not the least:
Study quant basics to death. Don't practice difficult combinatorics and probability questions unless you are 100 per cent confident in your basic quant abilities.
Don't be afraid to guess when the quant question is beyond your abilities – save time for other questions you know you are capable of.
Finally, take each GMATPrep test at least twice, preferably three times to get comfortable with the format of the exam.